diff --git a/em-oop/src/day3_123/Day3Check2.java b/em-oop/src/day3_123/Day3Check2.java
new file mode 100644
index 0000000..64d8e30
--- /dev/null
+++ b/em-oop/src/day3_123/Day3Check2.java
@@ -0,0 +1,15 @@
+package day3_123;
+
+public class Day3Check2 {
+	public static void main(String[] args) {
+		Rectangle rec = new Rectangle(3, 4);
+		rec.showInfo();
+		
+		
+		Greeting gre = new JapaneseGreeting();
+		System.out.println(gre.hello());
+	}
+	
+	
+
+}
diff --git a/em-oop/src/day3_123/Greeting.java b/em-oop/src/day3_123/Greeting.java
new file mode 100644
index 0000000..51c4d02
--- /dev/null
+++ b/em-oop/src/day3_123/Greeting.java
@@ -0,0 +1,6 @@
+package day3_123;
+
+public interface Greeting {
+	String hello();
+
+}
diff --git a/em-oop/src/day3_123/JapaneseGreeting.java b/em-oop/src/day3_123/JapaneseGreeting.java
new file mode 100644
index 0000000..74f8917
--- /dev/null
+++ b/em-oop/src/day3_123/JapaneseGreeting.java
@@ -0,0 +1,9 @@
+package day3_123;
+
+public class JapaneseGreeting implements Greeting {
+	@Override
+	public String hello() {
+		return "こんにちは";
+	}
+
+}
diff --git a/em-oop/src/day3_123/Rectangle.java b/em-oop/src/day3_123/Rectangle.java
new file mode 100644
index 0000000..a595cbb
--- /dev/null
+++ b/em-oop/src/day3_123/Rectangle.java
@@ -0,0 +1,18 @@
+package day3_123;
+
+public class Rectangle extends Shape {
+	private double width;
+	private double height;
+	
+	public Rectangle(double width,double height) {
+		super("四角形");
+		this.width=width;
+		this.height=height;
+	}
+
+	@Override
+	public double area() {
+		return width*height;
+	}
+
+}